Voice over internet protocol (VoIP) systems have become a basic tool with ever-growing popularity. However, they commonly rely on an unreliable communication channel, such as the internet, and are subject to frequent events of data loss. These events are usually realized in the form of lost data packets carrying audio information. This, in turn, leads to temporal gaps in received audio sequences. Left untreated, gaps create breaks in the audio (e.g. missing syllables in speech signals). High percentage of packet loss (for example, above 20%) can often render speech unintelligible.
FIG. 1A illustrates a VoIP system overview, in accordance with prior art. An acoustic signal is sampled at frequency fs, yielding sorg. It is then divided to packets, transmitted over an unreliable communication channel. Packets reaching their destination form sr. Some packets are dropped during transmission, causing sr to have sequences of missing samples.
For this reason, VoIP applications regularly incorporate a packet loss concealment (PLC) mechanism, to counter the degradation in audio quality. Many existing techniques have difficulties handling long audio gaps.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the figures.